Radiation therapy is a disease treatment using radiation such as X-rays, gamma rays, and proton beams. This retards or stops the growth of cancer tissues or various tissues of malignant diseases, and even kills such tissues.
In Korea, the number of new domestic cancer patients was 161,920 in 2007, and the occurrence frequency of cancers descends in order of stomach cancer, lung cancer, liver cancer, and cervical cancer. X-rays most dominantly play a role in treating cancers among diverse radiation treatments.
Generally, an X-ray treatment is a local/regional control therapy to treat a cancer in a region where it is difficult to undergo an operation for such reasons that the size of a tumor is very large and the depth of invasion is deep, or to treat a cancer which remains after an operation. Statistically, 60% of cancer patients undergo X-ray therapy.
In a conventional X-ray treatment, regional exposure of only the cancer tissue to X-rays is difficult to attain due to the characteristics of the X-rays which are emitted in a radial direction from an X-ray source, as illustrated in FIG. 1. That is, healthy cells and tissues in the vicinity of the cancer are also exposed to the X-rays. For this reason, a patient who undergoes the X-ray treatment suffers from side effects such as damage to healthy cells and tissues, hair loss, weakened immune system, and other complications.
In order to solve this problem, Intensity-Modulated Radiation Therapy (IMRT), Tomotherapy, Cyberknife therapy using a small linear accelerator, and the like have been developed and used.
However, in the case of IMRT and Tomotherapy, it is unavoidable that a large area including cancer tissue is exposed to X-rays, as illustrated in FIG. 2.
In the case of Cyberknife therapy, X-ray focusing is performed as illustrated in FIG. 3 so that highly-intensified narrow X-rays can be irradiated in various directions. Therefore, the Cyberknife therapy can be used for local therapy on the cancer tissue. However, the X-rays remain without being absorbed by the cancer cells or tissue after the focused X-rays are used to kill the cancer tissue, and scatter in all directions, negatively effecting human bodies. Therefore, the problem mentioned above still remains unsolved.
Accordingly, development of a novel radiation therapy which can minimize damage to healthy tissue other than patient's cancer tissue is still in demand.